Radio alarm system



April 29, 1941. w 055 2,239.;672

RADIO ALARM srs'i'lm j Filed Feb. 21, 1938 Patented Apr. 29, 19412,239,672" mm ALARM SYSTEM William L. Foss, Washington, D. 0., assignorto Howton Radio Alarm Company, Seattle, Wash.

Application February 21, 1938, Serial No. 191,787

Claims.

It is the object of this invention to provide an alarm system, and moreparticularly to provide an improvement upon the radio alarm system shownin the copending application of James O. Howton, Serial No. 184,713,filed January 12, 1938.

In the present invention an interrupter device is provided, in additionto voice message reproducing means, to impress a code message on thecarrier frequency in order that a suitable code message may be broadcastwhich will be intelligible even though an interfering voice broadcast,from another source, is occurring.

A preferred embodiment of the invention is diagrammatically shown inFigure l of the drawing. Figures 2 and 3 show a time control device,appearing also in Figure l, in other positions assumed by it during itscycle.

The transmitter and control system here shown are essentially the sameas that disclosed in the aforementioned Howton application. Severalchanges have been made in the wiring hook-up in order to connect thecode signalling means into the transmitter circuit.

The transmitter disclosed in the Howton application is designed tobroadcast on police and fire wave lengths. The protective system is soarranged that, when a burglar attempts to enter frequency is imposedupon the grid of a tube II, to the plate circuit of which is connectedan inductance I2. ,The inductance has a variable condenser l3 connectedacross its terminalsand a test jack l4 connected in line with a chokecoil l5 which is in series between one terminal of the inductance andthe positive terminal of a motor generator set IS. The test jack isprovided I through the series circuit containing choke' l5,

the secondary of a modulation transformer 2|, and a test jack 22. Jack22 provides a connecting means for a meter while tuning this stage ofamplification. A code signalling device .15

. connected in series-with the cathode of tube. [1,

the operation of'which will appear below.

the building or when a fire is detected,- an appropriate alarm messagewill be sent out to the authorities. The system embodies a relay controlmechanism that selectively actuates a voice alarm reproducing device tocause the desired message to be played into the transmitter and at thesame time renders the transmitter operative.

The present improved alarm system in addition to performing all of theabove also sends a code message. It has been found in practice that whenthe relatively low powered transmitter unit in the protected premises isbroadcasting and at the same time the central police radio transmitter,is broadcasting, the more powerful police station will interfere withthe voice message being sent out by the smaller. set. This diflicultyhas been overcome by providing a code signal in addition to the voicemessage. With this means it is possible to broadcast an intelligiblesignal over a wide area, for though interference will still take place,the code. message will over-ride and will be discernible over theinterfering voice messages of the central police broadcasting station.

Thetransmitter has a piezo-crystal ill to control the radio frequency.The controlled radio 55 the other element 32 of this P1 8 e tor to.

Modulation of the radio frequency is accomplished by impressing thevoice frequency upon the grid of a tube 23, the plate circuit of whichis connected to the grid of a tube 24 in the next stage ofamplification. The plate of tube 24 is connected to the primary of atransformer 25 the secondary of which is connected through a push pullcircuit 26 and 21 to the primary of modulation transformer 2|. Thesecondary of this modulation transformer is connected, as 'abovedescribed, into the plate of tube l1 and in this manner the voicefrequency is superimposed upon the carrier frequency.

I The modulated radio frequency currents thus created in the primarycoil IQ of a radio frequency transformer 30 induce a current fiow in itssecondary which is in the antenna circuit. This antenna circuit isgrounded through condenser 3i and the desired signal is thus broadcastedon the fire and police frequency to the fire and police authorities.

The above described circuit is designed to be compactly mounted within asuitable tamperproof casing and all the necessary leads are brought to acentral point where they are connected to a socket element 32a of themultiple point plug connector 32. The controlling means, responsive tothe burglar and fire alarm circuits of the building, is adapted to beconnected by the radio transmitting set to cause its operation when needbe.

The controlling means for causing the operation of the transmitter, thecode signalling device, and the voice alarm message reproducing means,is a system of relays connected between the fire and burglar alarmcircuits and the radio transmitter. An electrical pickup impresses arecorded voice alarm message on the audio stage of the transmitter, theparticular voice message which is broadcast depending upon which alarmcircuit is disturbed. If both circuits are disturbed the twomessageswill be broadcast in alternating relation as will appear more fully in;fire alarm circuit through the building is normally open and the burglaralarm circuit normally closed, as shown in Figure 1. When 2h: buildingis closed for the period to be protec e the apparatus-is set and throughthe circuit described below suitable relays are actuated to cause theoperation of the alarm message reproducing means and the transmitter.

A support bar provides a row of suitable contact points or terminals Ato J and the cor:i trolling circuit is hooked up through these poin inthe following manner:

' minal to points F, H, and J and with its negative rmm' al to point E,the negative side of the b l irglar and fire alarms being connected topoint E also. From point J a lead is provided that normally suppliescurrent through contact 34 to relay 33 to point I which forms thepositive or current supply terminal for the normally closed burglaralarm circuit. The point H is connected through normally deenergizedrelay 5! to point G.

The fire alarm circuit is connected across points E and G, this circuitnormally being open, a potential is established across its terminals,such that a current will fiow when the circuit is closed. Point F isconnected to the normally open contacts 35, 40 and 53. Whenever e therone of contacts 36 or 53 is made the circuit continues through relay 38,plug element 6|! of a two contact connector. The corresponding socketelement 60a of the connector continues the circuit through stop contact39, back to the plug 50, and then to the point E. If the contact 40 ismade the circuit continues through contact 4| to point C. The contact isconnected to the motor of the moton generator set l6, which motor is.

de to int D, which is connected to point lf on ectgi in parallel betweenpoints C and D are the motor 45 of the sound reproducing means and asupply for the filaments of the-tubes of the transmitter which supply isconnected to contacts 45 and 41 of plug element 32. The parallel circuitincluding the motor 45 has a switch 6|, connected in series with themotor, that may be manually operated or that may be actuated by thevoice alarm message reproducer to stop this voice alarm mechanism.Connected across points 45 and 41 of socket element 32a is a circuitthrough the motors 58 and 59 of the code i allin means. 'l l' he positive side of the generator of the motor generator set is connected topoint A, the negative side to point B. Point A is connected to contact43 of plug 32. Point B is connected to contact 44 and also forms aground for the pickup arms 50 and 5|. The pickup 55 is connected intocircuit through the transmitter by contact 31 of relay 33, one side ofthe contact 31 being connected to contact 43 of plug 33. Pickup 5| isconnected to contact 54 of relay 53, contact 54 being connected inparallel with contact 31.

The code signalling means is connected with the transmitter circuit in aseries circuit including tube H in the second stage of the radiofrequency circuit. In the preferred form the code signalling meanscomprises a wheel 52 havinga suitable code provided on its periphery. Acontact arm 84 is adapted to engage the periphery of the wheel and itsrotation makes and breaks the circuit through the contact arm inaccordance with the code. The contact arm being in series with thecathode of tube II, when the wheel is rotated the cathode circuit isalternately made and broken in a sequence such that the code isimpressed upon the carrier frequency. It is obvious, of course, that thecode message provided on the periphery of the rotating wheel is such asto apprise the authorities of a disturbance of one of the protectivesystems about the premises.

The above described circuits being established, the apparatus operatesin the following manner:

When neither the fire nor burglar alarm circuits are disturbed the relay33 remains energized by holding contact 34' closed establishing anenergizing or holding circuit through battery 35. Relays 33 and 52remain deenergized. This condition will prevail until the burglar alarmcircult in series with the battery and relay 33, is broken or the firealarm circuit is made.

When the burglar alarm circuit is broken, it being in series with thebattery and the relay 33, the, current supply to the relay is stopped.Consequently the relay is deenergized and contact 34 is broken. While atthe same instant contacts 33 and 31 are made. The breaking of contact 34deenergizes relay 33 and to again become operative it must be manuallyreset. When contact 36 is made current is supplied from the positiveterminal of the battery, to a circuit containing the relay 38, connectorill and the contact 39, back to the negative of the battery. Theenergization of relay 3!! makes contacts 43 and 4|. The contact 40 beingconnected to the positive side of the battery, a current supply circuitis established through contact 4| to the motor of the motor generatorset I6, which is grounded to the battery and the generator is operatedto supply a suitable current (400 volts) to the radio transmitterthrough contact points 43 and 44 of plug member 32. Being connected inparallel with the motor circuit of the motor generator IS, the smallmotor 45 arranged to drive a turntable and the stop switch 5| connectedin series therewith and the current supply through contacts 45 and 41 ofplug 33 to the filaments of the radio transmitter tubes, these elementsof the system are rendered operative by the closing of contacts 43 and4|. The energization of contacts 45 and 41 of socket element 32a causesthe operation of the motors 58 and 65 of the code signalling means.

The code signalling device is designed to operate for a short periodbefore the. voice alarm message is permitted to be sent. Then the codemessage is blanked out for an interval and the voice alarm message isrendered intelligible throughout the area where no interference takesplace. After the voice alarm message has been broadcast for a sufflcientperiod, the code signalling device is again connected into the circuitso that the code message is impressed upon the carrier wave and sendsthe code message into such areas in which the voice alarm may have beeninterfered with.

To perform the above sequence of operations the cam element 66 is drivenby the motor 63.

and the code wheel 62 is driven by motor 63.-

These motors connected in parallel with the filament supply areenergized as above explained and through suitable gear trains drive thecam and code wheels respectively. At the beginning of operations the camwheel is in the position shown in Figure 1. Surface does not engagecontact 66 and the code message is impressed upon the carrier frequencyas above described. When the cam has rotated to the position shown inFigure 2 surface 10 engages contact 66 short circuiting the code wheeland rendering the cathode continuously energized while the contactcontinues in engagement with the surface so that the voice alarm may bebroadcast. As the cam continues its rotation and surface 10 isdisentracks is in position on the turntable and each track cooperateswith a suitable electrical pickup. The two tracks are provided on onerecord so that from one track a message that the building is beingbroken intomay be reproduced and from the other a message may bereproduced to the effect that a fire has been detected. The recordingson the difierent tracks are so related that in the case where bothburglar and fire messages are required, first the burglar message 'willbe given, then the fire message, the alarm messages will alternate inthis manner, until the starts the transmitter, code sending device, andturntable. The making of contact 64 establishes a circuit through thefire message pickup ii and the grid of tube 23 of the audio-frequencystage of the transmitter. In this manner the code and voice alarmmessages are broadcast calling attention to a. fire within the protectedarea.

In the event that the burglar and fire alarm circuits should both bedisturbed the relay 33 is deenergized and relays 33 and 52 areenergized. The deenergizationof relay 33 energizes relay 33 to set thetransmitter and code device in operaand the transmitter is thrown out ofoperation.

tion and establishes a circuit through pickup 60. The energization ofrelay 62 establishes a circuit through pickup 5|. The transmitting setunder these circumstances having both pickups and the code device incircuit with'it, broadcasts both voice and code alarm messages. Therecord from which the voice alarm messages are being reproduced havingthe two nonconfiicting series of tracks as above explained, the alarmmessages do not interfere with one another when the voice v alarm isbeing broadcast.

If the. transmitter should accidentally be set in operation, in order toprevent false alarms being sent out a manual controlof the contact 39 isprovided. It is possible by operating this contact to break the currentsupply through the relay 33. When this happens contacts 40 and it arereleased and break contact, the current supply to the motor of motorgenerator I6 is stopped,

It is, of course, obvious that the set and the contact would be situatedin some concealed position to render it inaccessible to unauthorizedpersons.

Whenever the protective system has been called into action it willcontinue to broadcast for a predetermined period of time. This period iscontrolled by the arm 61 of the cam and contact 33, 1. e. the set willbroadcast until the arm actuates the contact. This, as above explained,

sound reproducer is stopped by the actuation of respectively. As abovestated the deenergization of relay 33 causes contacts 36 and 31 to bemade. The circuits established by contact 36 prepare the radiotransmitter for operation. The making of contact 31 connects the burglarmessage pickup into a circuit through the plug 32 to the grid of tube 23of the audio frequency stage. The transmitter already being in operationthe appropriate message reproduced through pickup 50 will be broadcasttothe police authorities. 4

Referring to the condition of the alarm system when it has been properlyset for guarding the building it will be remembered that the relay 33 isenergized holding contacts 36 and 31 broken and making contact 34. Inthis circumstance when the fire alarm circuit is made, i. e. when athermostat-in the circuit is heated to such a temperature indicative offire that it closes the circuit, a current is caused to fiow in relay 52stops the motor generator set and renders the transmitter inoperative.In order to again condition the set for operation it is necessary toreset the relay control system. This is done by closing the burglaralarm circuit and/or opening the fire circuit making it possible toreenergize relay 33 by making contact 34. The cam 65 is reset and alsopickup arms 50 and 5i. The contact 33 is made and the system is inoperative position to protect the building.

The relay control system like the transmitter is compactly designed tofit within a tamperproof casing and has all of its leads that cooperatewith the transmitter brought out to the plug element 32 of the multipleconnector and plug element 60 of the two point connector. The otherleads of the control system, which are connected to the burglar. andfire alarm "circuits, the battery, and the motor generator set arebrought any building to be protected by this apparatus is first wiredwithproperly designed fire and burglar alarm circuits. These circuitsare connected to the terminal support bar of the concealed control unitand the control unit is plugged into the transmitter unit. As soon as abattery and motor generator set have been connected up, the system is incondition for operation. By this means a thoroughly reliable, compact,and simple broadcasting station is situated in the building to beprotected and the unit is effective to automatically call the P liceand/or fire department upon any tampering with the building.

It is obvious, of course, that the normally closed burglar alarm and thenormally open fire alarm circuits could be interchanged so that aclosing of the burglar circuit and an opening of the fire circuit wouldinitiate operations. However the preferred hookup is as above described.Other modifications will appear to those skilled in the art, all ofwhich are included within the scope of the appended claims.

I claim:

1. A radio alarm system comprising a transmitter including a pluralityof tubes and alarm message producing means in connection with saidtransmitter, said means including code signalling means and a motor forsaid last named means, means for blanking out said code signalling meansand a motor to drive said blanking means, said motors being connected inparallel with each other and in parallel with the filament supplycircuit for said tubes, means for controlling the operation of the lastnamed means, said alarm message producing means including also voicemessage producing means, and means for operatively connecting said voicemessage producer with the transmitter while the code Signalling means isblanked out, said alarm system being adapted to transmit a warning of adisturbance on a protected premise, said voice message producing meansbeing eifective when actuated to cause a warning signal to be broadcastand said code signalling means being effective when actuated to send anintelligible signal into zones of possible interference.

2. A radio alarm system comprising a transmitter and alarm messageproducing means in connection with said transmitter, said meansincluding code signalling means, means for blanking out said codesignalling means including a plurality of successively operated circuitcontrols,

one of said contacts making a short circuit around said code signallingmeans, another of said contacts being operative to stop saidtransmitter, means for controlling the operation of said blanking outmeans, said alarm message producing means including also voice messageproducing means, and means for operatively connecting said voice messageproducer with the transmitter while the code signalling means is Iblanked out, said alarm system being adapted to transmit a warning of adisturbance on a protected premise, said voice message producing meansbeing effective when actuated to cause a warning signal to be broadcastand said code signalling means being effective when actuated to send anintelligible signal into zones of possible interference.

3. An alarm system including a radio transmitter havihg an audiofrequency stage and a radio frequency stage, said last named stageincluding a cathode tube, a plurality of different voice alarm messages,means to cause said different messages to be selectively impressed uponsaid audio frequency stage, a code message adapted to be impressed uponthe cathode of said tube, means to initiate said voice alarm and saidcode alarm to cause a broadcast thereof, and means to cause said codemessage to override said voice alarm at spaced time intervals wherebythe alarm signal is transmitted to distant points irrespective of othervoice messages which may be being broadcast on the same wave band assaid radio transmitter.

4. An alarm system including a radio transmitter having an audiofrequency stage and a radio frequency stage, a plurality of diflerentvoice alarm messages, means to cause said different messages to beselectively impressed upon said audio frequency stage, a code messageadapted to be impressed upon said radio frequency stage, means toinitiate said voice alarm and said code alarm to cause a broadcastthereof, said means comprising a plurality of protective circuits wiredaround the premises, a relay system between said circuits and saidtransmitter controlled by said circuits, said relay system beingeffective to cause an energization of said transmitter and selectivelyimpress the voice alarm message to be broadcast on the carrierfrequency, and means to cause said code message to override said voicealarm at, spaced time intervals whereby the alarm signal is transmittedto distant points irrespective of other voice messages which may bebeing broadcast on the same wave band as said radio transmitter.

5. An alarm system including a radio transmitter having an audiofrequency stage and a radio frequency stage, said last named stageincluding a cathode tube, a plurality of different voice alarm messages,means to cause said different messages to be selectively impressed uponsaid audio frequency stage, a code message adapted to be impressed uponthe cathode of said tube, means to initiate said voice alarm and saidcode alarm to cause a broadcast thereof, and means to cause said codemessage to override said voice alarm at spaced time intervals, said lastnamed means including a code producing device and a time driven circuitmaker and breaker, said circuit maker and breaker comprising a contactwheel and switch actuating finger serving to sequentially connect saidcode producing means into series with said cathode tube and then shortcircuit and code producing means and then again connect said codeproducing means in series with said cathode and then said finger servingto break the energizing circuit of said transmitter, whereby the alarmsignal is transmitted to distant points irrespective of other voicemessages which may be being broadcast on the same wave band as saidradio transmitter.

WILLIAM L. FOSS.

